⚠️ After a long, fruitful career, Disco Labs has deprecated the use of this gem internally. Over time, much of the functionality developed in DiscoApp has been replicated or merged into the official ShopifyApp gem, which has also better kept up to date with substantial changes in the way Shopify Apps are built such as session token authentication.

Third party developers who have been relying on this gem are welcome to fork and use it as needed, and if there's a pressing need, pull requests and new releases can be actioned, but no active development will take place in this repository.

DiscoApp Rails Engine

A Rails Engine encapsulating common functionality for Disco's Shopify applications.

Aims to make it a cinch to get a new Shopify application up and running, as well as providing common functionality in a single codebase.

• Getting Started
• Engine Overview
• Troubleshooting
• Contributing

Getting Started

Spinning up a new Shopify app with this engine is a simple four-step process, detailed below.

1. Setting up

First make sure you've got all of the tools you need for Shopify and Rails development. You should read through the [Getting Started] board in Notion and make sure you've followed all setup instructions there, specifically the cards on Development Setup and Development Configuration. The key things to note are:

• You should have set up a Shopify Partner account to allow you to create development stores and applications;
• asdf is recommended for Ruby version management;
• You should have the latest version of Ruby 2.6 installed locally, along with the rails and bundler gems (make sure you have the version of Rails you'd like to use installed - use gem install rails -v VERSION for this);
• You should have ngrok installed for HTTP tunnelling;
• You should have followed the instructions in the Development Configuration Notion card for configuring Bundler with credentials to access Disco's private Gemfury server.
• You should have followed the instructions in the Development Configuration Notion page to have generated a personal access token on Github and added it to your development configuration.

2. Creating the Rails app

Running the following command from your terminal to create a new Rails app, add the DiscoApp Rails Engine to your Gemfile, and set up the Engine:

curl -H "Authorization: token $GITHUB_PERSONAL_ACCESS_TOKEN" \
     -H "Accept: application/vnd.github.v4.raw" \
     -L "https://raw.githubusercontent.com/discolabs/disco_app/master/initialise.sh" \
     | bash -s example_app

Be sure to change example_app to the desired name of your actual application. Also, if you are stuck at any point in the initialise process, hit ctrl-c and do spring stop in the folder and run bundle exec rails generate disco_app:install --force to continue the process.

By default, the initialise.sh script uses the latest version of Ruby, Rails, Node and the DiscoApp framework. If for any reason you need to specify which version of each of these to use, you can provide them as arguments on the last line. For example, to use Rails 4.2 with Ruby 2.4.1, Node 10.19 and DiscoApp version 0.13.8, the last line of the command above should read:

    | bash -s example_app 4.2.0 2.4.1 10.19 0.13.8

Once this is complete, you'll have a new Rails app created in /example_app, with the DiscoApp Engine configured and mounted.

3. Setting up the Shopify app

In order to work on our app, we need to create a development application from the Shopify Partners dashboard. Once that's done, we can copy across the generated API credentials to our development app and perform a test install.

DiscoApp provides a command line utility to quickly generate a new Shopify app via the partner dashboard. Before you can do this, you need to configure a couple of things.

Create a DiscoApp configuration file in your home directory

First, you'll need to add your partner dashboard credentials to a DiscoApp configuration file in your home directory, ~/.disco_app.yml:

params:
  PARTNER_EMAIL: "[email protected]"
  PARTNER_PASSWORD: "***********"
  PARTNER_ORGANIZATION: "Disco"

Configure initial values in local ENV file

Next, you'll need to set a few of the basic configuration parameters for your app in .env.local in the application directory. The command line utility will use these to configure your app.

You'll need to set values for DEFAULT_HOST (the base URL for your application, for example https://example-app.ngrok.io) and for SHOPIFY_APP_NAME (the name of the application).

Creating and configuring your app

With the above set up, should head to Create an app to create your app.

As you are creating your app, please take note of the details and fill the following in the .env.local file:

DEFAULT_HOST=https://example.ngrok.io

SHOPIFY_APP_NAME=Example App
SHOPIFY_APP_API_KEY=ebef81bcfe2174ff2c6e65f5c0a0ba50
SHOPIFY_APP_SECRET=d5e1347de6352cb778413654e1296dde
SHOPIFY_APP_REDIRECT_URI=https://example.ngrok.io/auth/shopify/callback

The .env.local file would also require the following:

SHOPIFY_APP_SCOPE=read_products,read_orders,write_orders,write_script_tags
SHOPIFY_APP_PROXY_PREFIX=/a/example

SHOPIFY_CHARGES_REAL=

SECRET_KEY_BASE=

REDIS_PROVIDER=

If you need help filling in the scope, here is a list of scope

Notice that .env.local should not be added to Git, and is therefore added to .gitignore. On the other side, .env is added to Git and should keep all the environment variables that are kept equal across the different environments.

Finally, you'll want to add a subscription. Subscriptions are covered in more detail in the Plans, Subscriptions, and Charges section. For now, we just want our stores to subscribe to a free plan. To do this, we need to add something like the following snippet to the db/seeds.rb file.

DiscoApp::Plan.find_or_create_by(
  name: 'My Free App',
  amount: 0,
  trial_period_days: 0
)

Run rails db:seed and you're done!

4. Putting it all together

Finally, we're ready to test the installation of the development app. First, fire up your tunneling software to proxy requests to port 3000 on your local machine. For example, if using ngrok:

$ ngrok http -subdomain=example 3000

In another terminal window, start up the Rails webserver. The DiscoApp generator provides a Rake task to easily start the server:

$ rake start

Now you should be able to visit the root URL of your app in the browser (eg https://example.ngrok.io) and be presented with the login screen. Enter the name of a development Shopify store, and you should be taken through the process of authorising and installing the application to the store.

If you don't have a development store to test with, you can create one from the Shopify Partner dashboard in a similar manner to creating a development app.

Note: It's important to access your local development app via SSL (ie, https://example.ngrok.io rather than http://example.ngrok.io. Otherwise, the URLs generated during the OAuth flow won't match your application settings and you won't be able to install the app.

Engine Overview

The DiscoApp Rails Engine incorporates and extends the functionality provided by the ShopifyApp Rails Engine, which is an official gem developed by Shopify.

Environment and Configuration

The following gems are added during setup:

• shopify_app for basic Shopify application functionality;
• puma for serving the app in development and production;
• sidekiq for background job processing in production;
• pg for Postgres use in all environments: development, test and production;
• dotenv-rails for reading environment variables from .env files in development;
• rails_12factor for use with Heroku/Dokku in production;
• activeresource for Shopify to communicate with REST web service;
• mailgun_rails for sending email programatically via the Mailgun service;
• premailer_rails support for styling HTML emails with CSS;
• rollbar Exception tracking and logging;
• newrelic_rpm New Relic RPM Ruby Agent.

The following configuration changes are made:

• Force SSL in production;
• Use Sidekiq as the ActiveJob queue adapter in production;
• Set the default host in the router to allow absolute URL reversal;
• Turn off prepared statements for Postgres databases.

Finally, the following environment changes are made:

• Add .ruby-version file and update Gemfile to lock down Ruby version being used;
• Add default .env and .env.local files for development environment management;
• Add a Procfile for deployment to Heroku;
• Add a CHECKS file for use with Dokku deployments
• Update the .gitignore with some additional useful defaults.

Authentication, Sessions and the Shop Model

The functionality provided by the ShopifyApp engine includes support for OAuth authentication and storing session information in a Shop model. The gem also provides a SessionsController which is used to log in and authenticate with Shopify.

During installation and setup, a DiscoApp::Shop model is created, which stores the domain name and API token for a shop that installs the app, along with a number of other attributes such as email address, country, Shopify plan type, et cetera.

User Authentication

In addition to providing built-in OAuth authentication at the Shop level by default, the gem allows you to enforce authentication at the user level.

To use this functionality, you will need to include the DiscoApp::Concerns::UserAuthenticatedController concern on any controller that requires an authenticated user. Once authenticated, this concern will ensure a @user instance variable is present on the controller.

You will also need to replace the contents of config/initializer/omniauth.rb with the below code:

module OmniAuth::Strategies
  class ShopifyUser < Shopify
    def name
      :shopify_user
    end
  end
end

SETUP_PROC = lambda do |env|
  env['omniauth.strategy'].options[:per_user_permissions] = true
  params = Rack::Utils.parse_query(env['QUERY_STRING'])
  env['omniauth.strategy'].options[:client_options][:site] = "https://#{params['shop']}"
  env['omniauth.strategy'].options[:old_client_secret] = ShopifyApp.configuration.old_secret
end

Rails.application.config.middleware.use OmniAuth::Builder do
  provider :shopify,
    ShopifyApp.configuration.api_key,
    ShopifyApp.configuration.secret,
    scope: ShopifyApp.configuration.scope
  provider :shopify_user,
  	ShopifyApp.configuration.api_key,
    ShopifyApp.configuration.secret,
    scope: ShopifyApp.configuration.scope,
    setup: SETUP_PROC
end

Plans, Subscriptions, and Charges

The gem provides a framework for billing merchants for the use of applications. This framework consists of plans, subscriptions, plan codes, and charges.

Plans represent the different pricing levels you can offer your merchants. They are configurable from the application admin pages (if enabled for the app in question), allowing application owners to set different prices, trial periods, and charging patterns.

Subscriptions are the mapping between a particular shop and their current plan. A shop can only have a single active subscription at a time.

Plan Codes belong to a particular plan, and allow for a particular store to have their subscription to a plan adjusted or discounted. For example, if you have a "Premium" plan, you might add a Plan Code to it with a code PODCAST for your podcast listeners that reduces the monthly price by 10% and extends the trial period to 60 days.

Charges are a local representation of the Shopify charge objects that are created and approved by merchants. The appropriate charge object is generated based on a current store's subscription.

The DiscoApp::Concerns::AuthenticatedController concern (which should be included by all embedded application controllers in an app) performs a series of checks to make sure that the current user is able to access the insides of the page. It:

• Checks the shop has an authenticated session. If not, redirects to the OAuth authentication flow provided by the ShopifyApp gem;
• Checks the shop has completed the installation steps. If not, redirects to begin the installation process.
• Checks the shop has a currently active subscription. If not, redirects to the new subscription selection controller.
• Checks the currently active subscription has a valid, active charge (or that the currently active subscription doesn't require a charge, as may happen when the amount to be charged is zero). If not, redirects to begin the charge approval process for the current subscription.

If you're building an app that doesn't need to worry about charging store owners, you should ensure it creates a Plan with an amount value of zero, and that all stores are subscribed to that plan during DiscoApp::AppInstalledJob.

The default set of plans for your app should be placed into the db/seeds.rb file. Make sure you run rails db:seed after resetting your database to ensure the plans are correctly set up.

Whenever a store's subscription level is changed, DiscoApp::SubscriptionChangedJob is queued.

Rake Tasks

There's a number of useful Rake tasks that are baked into the app. They are:

• rake start: Spin up a local Puma development server, bound correctly to the local IP.
• rake webhooks:sync: Trigger a re-synchronisation of webhooks for all shops on active Shopify plans and with the application currently installed.
• rake database:update_sequences: Update postgres sequence numbers in case the database has been imported or migrated.
• rake shops:sync: Synchronises shop data across all installed shops.
• rake users:sync: Synchronises user data across all installed shops.

Background Tasks

The DiscoApp::ShopJob class inherits from ActiveJob::Base, and can be used to queue jobs that need to take place in the API context of a particular shop. This means that inside the perform method of a ShopJob, all API calls will automatically be made on behalf of the shop, like so:

class FindAllProductsJob < DiscoApp::ShopJob
  def perform(_shop)
    ShopifyAPI::Product.find(:all)
  end
end

Note that the first argument of the perform method on any job inheriting from DiscoApp::ShopJob must always provide the shop context the job is executing in (the shop argument above). This can be done either by providing a DiscoApp::Shop instance directly (preferable) or by providing the Shopify domain of the shop as a string (eg example.myshopify.com).

The gem includes some default jobs that are queued during installation or after specific webhooks are received. They are:

• DiscoApp::AppInstalledJob, triggered when the application is installed. By default, this job uses the Shopify API to set up webhooks and to perform initial data synchronisation.
• DiscoApp::AppUninstalledJob, triggered when the app/uninstalled webhook is received. By default, this job simply updates the status flag on the DiscoApp::Shop model, but you may wish to add tasks like sending a cancellation email or the like.
• DiscoApp::ShopUpdateJob, triggered when the shop/update webhook is received. By default, this task keeps the metadata attributes on the relevant DiscoApp::Shop model up to date.
• DiscoApp::CustomersDataRequestJob, triggered when the customers/data_request webhook is received. By default, this does nothing.
• DiscoApp::CustomersRedactJob, triggered when the customers/redact webhook is received. By default, this does nothing.
• DiscoApp::ShopRedactJob, triggered when the shop/redact webhook is received. By default, this does nothing.
• DiscoApp::SubscriptionChangedJob, called whenever a shop changes the plan that they are subscribed to.
• DiscoApp::SynchroniseWebhooksJob, called by the installation job but also enqueued by the webhooks:sync rake task to allow for re-synchronisation of webhooks after installation.
• DiscoApp::SynchroniseCarrierServiceJob, called by the installation job but also enqueued by the carrier_service:sync rake task to allow for re-synchronisation of the carrier service after installation.

The default jobs that come with the engine can be extended through the use of Concerns in a similar way to the models that come with the engine. See Extending Models below.

Additionally, the gem includes DiscoApp::SynchroniseResourcesJob. It takes a synchronisable class name (like Product) and a params hash, which it then uses to fetch a list of resources via the API. So if we wanted to synchronise products with the ids 123, 456 and 789, we could do:

DiscoApp::SynchroniseResourcesJob.perform_later(shop, 'Product', ids: '123,456,789')

Webhooks

As you may have noticed from the preceding section, webhooks and background tasks are closely linked. The DiscoApp Engine routes requests to /webhooks to the process_webhook method on DiscoApp::WebhooksController.

When the controller receives an inbound webhook, it is automatically verified using the application's secret key. The controller then attempt to queue a job matching the topic name of the incoming webhook (eg app/uninstalled will try to queue a job named DiscoApp::AppUninstalledJob). Two arguments will be passed to the job's perform method: the domain of the shop the webhook was related to, and the JSON payload of the webhook as a hash.

There shouldn't be any need to extend or override DiscoApp::WebhooksController inside an application - all application logic should simply be placed inside the relevant *Job class.

The registration of webhooks for a shop is typically handled automatically by the DiscoApp::SynchroniseWebhooksJob background job, which is either queued automatically on installation (the default DiscoApp::AppInstalledJob) does this) or by the webhooks:sync rake task.

To check which webhooks are currently registered by your app for any given shop, you can run the following from the Rails console:

shop = DiscoApp::Shop.find(your_shop_id)
shop.with_api_context { ShopifyAPI::Webhook.find(:all) }

All application are configured to register webhooks for the app/uninstalled and shop/update webhook topics, as these are almost always required. Additional webhook topics can be defined in config/initializers/disco_app.rb, with:

DiscoApp.configure do |config|

  config.webhook_topics = [:'orders/create', :'orders/paid']

end

By default, webhooks will be registered with an empty fields attribute (meaning all object fields will be sent in the payload). This can be overridden on a per-topic basis with the optional webhook_fields configuration option:

DiscoApp.configure do |config|

  config.webhook_fields = {
    'orders/paid': [:id, :financial_status]
  }

end

Shopify Flow

The gem provides support for Shopify Flow Connectors, allowing applications built with this framework to define and send triggers and receive and process actions. Each trigger that's created or action that's received is stored in the database as DiscoApp::Flow::Trigger and DiscoApp::Flow::Action models respectively.

Triggers and actions are processed asynchronously as background jobs. The success or failure of a trigger or action is stored in a status attribute in the models. If a trigger or action fails for any reason, the reported reasons for failure are stored in a processing_errors attribute.

Applications that are sending a lot of triggers, or receiving a lot of actions, may want to clear out the trigger and action database tables periodically.

Triggers

Shopify Flow Triggers are events that happen inside a Shopify app that can be used inside Shopify Flow to start workflows. There's no special configuration that you need to undertake to start using Flow triggers with a Disco App - assuming that you've defined a trigger in your application's configuration from the Shopify Partner dashboard, you can fire that trigger with the following code:

DiscoApp::Flow::CreateTrigger.call(
  shop: @shop,
  title: 'Customer became a VIP',
  resource_name: 'Customer Jane Doe',
  resource_url: 'https://store.myshopify.com/admin/customers/734299256292',
  properties: {
    'Customer email' => '[email protected]'
  }
)

Upon execution, a new DiscoApp::Flow::Trigger model will be persisted and a background job enqueued to send the trigger information to the relevant Shopify store's GraphQL API endpoint.

The arguments passed to the CreateTrigger method are:

• shop: The relevant DiscoApp::Shop instance the trigger relates to;
• title: The title of the trigger. This must exactly match the title of the trigger as defined from the Shopify Partner dashboard;
• resource_name: A short description of the object the trigger relates to. This is used by the Shopify Flow app to display workflow event history to store owners;
• resource_url: A URL that can be followed by a store owner to view more information about the object the trigger relates to;
• properties: A payload hash containing data about the trigger event that can be used by merchants within their workflows. The presence and data types of the values in this hash must exactly match those configured for the relevant trigger in the Shopify Partner dashboard.

Trigger Usage Monitoring

After the initial introduction of Shopify Flow, Shopify added support for sending a special Shopify Flow webhook to applications to let them know when their Flow triggers were or weren't being actively used by merchants. Having this information means apps can avoid making redundant Flow trigger API calls.

Disco App provides built-in support for processing the information provided in these webhooks, keeping track of current trigger usage for each installed shop, and skipping the trigger API call in situations where we know it isn't being used by a merchant. It does this by providing a DiscoApp::Flow::TriggerUsageController endpoint, alongside a DiscoApp::Flow::TriggerUsage model to track usage in the database.

The only thing you'll have to do if you'd like your app to take advantage of this functionality is update the "Extensions... Shopify Flow... Webhook configuration" setting for your application in the Shopify Partner dashboard. You should set the webhook URL to point to the /flow/trigger_usage path for your app, eg https://example.discolabs.com/flow/trigger_usage.

Actions

Shopify Flow Actions are the operations a Shopify application can perform as part of a workflow. Like Triggers, Actions must be defined within the Shopify Partner Dashboard configuration page for the application. The Disco App gem provides an DiscoApp::Flow::ActionsController, which serves a similar function to the DiscoApp::WebhooksController - it receives and verifies incoming requests from Shopify before handing them off for processing.

Unlike webhook processing, incoming actions are persisted to the database in the form of a DiscoApp::Flow::Action model before being processed. When attempting to process an action, Disco App will attempt to find, instantiate and call a service object with the same name as the action_id of the relevant action. The action_id is determined by the URL used by Shopify to send the action payload.

To take an example, an action may be configured in the Shopify Dashboard with the following attributes:

• Action title: Email customer;
• Action description: Send an email to a customer;
• HTTPS request URL: https://example.discolabs.com/flow/action/email_customer.

When Shopify sends a request for this action, the action_id of the persisted action model will be email_customer (derived from the request URL). When trying to process this action, Disco App will attempt to look for either an EmailCustomer or Flow::Actions::EmailCustomer service object class within the current application. If found, the call method will be called on that object with the relevant DiscoApp::Shop instance and the provided action properties hash being passed as keyword arguments - essentially, something like this:

Flow::Actions::EmailCustomer.call(shop: action.shop, properties: action.properties)

In this way Disco App expects applications using Shopify Flow actions to define service objects to process those actions using a typical Disco interactor pattern.

Configuration

Strictly speaking, the only two things that need to be done inside application code to support Shopify Flow Actions and Triggers are:

1. Call DiscoApp::Flow::CreateTrigger anywhere in your code where a trigger should be fired;
2. Create a Flow::Actions::ActionName service object class for each action you'd like your application to be able to process.

Assuming you've configured your application's Flow integration correctly from the Shopify Partner dashboard, the sending of triggers and receiving of actions should then "just work".

However, to help maintain an overview of the actions and triggers supported by your application with its codebase, it's recommended to maintain two additional initializers in your application's configuration that describe them. These files should then be treated as the source of truth for your application's actions and triggers, and should be referenced when setting up or updating your application's Flow configuration from the Partner Dashboard.

Examples of each initializer follow.

# config/initializers/disco_app_flow_actions.rb
DiscoApp.configure do |config|
  config.flow_actions = {
    email_customer: {
      title: 'Email customer',
      description: 'Send an email to a customer',
      properties: [
        {
          name: 'customer_email',
          label: 'Customer email',
          help_text: 'The email address of the customer.',
          type: :email,
          required: true
        }
      ]
    }
  }
end

# config/initializers/disco_app_flow_triggers.rb
DiscoApp.configure do |config|
  config.flow_triggers = {
    customer_became_a_vip: {
      title: 'Customer became a VIP',
      description: 'A customer successfully qualified for VIP status.',
      properties: [
        {
          name: 'Customer email',
          description: 'The email address of the customer.',
          type: :email
        }
      ]
    }
  }
end

In future versions of Disco App, the creation of triggers and the processing of actions may be validated against the schema defined in these initializers.

Asset Rendering

It's a pretty common pattern for apps to want to render and update Shopify assets (Javascript, stylesheets, Liquid snippets etc) whenever a store owner makes particular changes to a configuration object. To make this pattern easy to implement, the gem provides a renders_assets macro, which you can use to define one or more "asset groups" to render when particular attributes on a model change. Here's an example:

# app/models/widget_configuration.rb
class WidgetConfiguration < ActiveRecord::Base
  include DiscoApp::Concerns::RendersAssets
  renders_assets :js_asset, assets: 'assets/widgets.js', triggered_by: 'locale'
end

With this simple declaration, any time the locale attribute on a particular WidgetConfiguration model changes, an asset template (in this case, located at app/views/assets/widgets.js.erb) will be freshly rendered and and uploaded to the current Shopify theme as assets/widgets.js. The template itself might look like this:

// app/views/assets/widgets.js.erb
(function() {
  var locale = '<%= @widget_configuration.locale %>';
})();

Both the assets: and triggered_by: options handle lists, so you can specify more than one asset to render and more than one triggering attribute. What's more, if you specify a list of assets:, then the public CDN url of assets earlier in the list will be available in the templates of subsequent assets, like this:

# app/models/widget_configuration.rb
class WidgetConfiguration < ActiveRecord::Base
  include DiscoApp::Concerns::RendersAssets
  renders_assets :widget_assets, assets: ['assets/widgets.scss', 'assets/widgets.js'], triggered_by: ['locale', 'background_color']
end

// app/views/assets.widgets.scss.erb
#widget {
  background-color: <%= @widget_configuration.background_color %>;
}

// app/views/assets/widgets.js.erb
var locale = '<%= @widget_configuration.locale %>';
var cssUrl = '<%= @public_urls[:'assets/widget.scss'] %>';

Finally, you can pass the name of one or more Javascript assets in a script_tags: option. If specified, the asset renderer will ensure that a Shopify script tag resource is created (or updated) pointing to your newly rendered asset:

# app/models/widget_configuration.rb
class WidgetConfiguration < ActiveRecord::Base
  include DiscoApp::Concerns::RendersAssets
  renders_assets :widget_assets, assets: ['assets/widgets.scss', 'assets/widgets.js'], script_tags: 'widgets.js', triggered_by: ['locale', 'background_color']
end

Application Proxies

The gem provides support for Shopify's Application Proxy functionality through a controller concern named DiscoApp::Concerns::AppProxyController. Including this concern on any controller will automatically verify each incoming request to make sure it's coming from Shopify (see the security section) in the Shopify documentation. Note that by default this check is only performed in production environments.

The DiscoApp::Concerns::AppProxyController also alters the response headers to return an application/liquid MIME type by default, to allow the processing of Liquid by Shopify before returning the response to the user. If you'd like to return plain HTML and avoid Liquid processing, you can add a skip_after_action directive on your controller targeting the :add_liquid_header method.

Here's an example controller using the concern, that will return plain HTML from its index action and Liquid from its show action:

class MarblesController < ApplicationController
  include DiscoApp::Concerns::AppProxyController

  skip_after_action :add_liquid_header, only: [:index]

  def index
    @marbles = Marble.all
  end

  def show
    @marble = Marble.find(params[:id])
  end
end

Note that in this instance it's important that ApplicationController doesn't perform any login authentication, as no session information is made available in proxied requests.

Models in Liquid

If you're making use of an application proxy, you'll often want to provide data from one or more of your application's models to a Liquid template. In fact, we've generally found that the best pattern for app serving app proxy pages is for the app to return a Liquid template with no HTML at all - only relevant data and an {% include 'some-snippet' %} call.

This pattern allows the complete customisation of front end pages via the shop's theme, placing control of the appearance of your app's pages squarely under the control of the merchant. Your application can (in fact, it should) render some default snippets into the theme on installation to give merchants something that works out of the box.

To make the process of providing model data to Liquid templates, the DiscoApp Engine provides the DiscoApp::Concerns::CanBeLiquified concern. It will use the model's as_json method to get a list of serialised attributes for your model and returns the necessary Liquid {%- assign -%} tags to provide that data inside a template.

As an example, if you had a model MyModel that you wanted to render via an application proxy, you would have the following in your application's app/models/my_model.rb:

class MyModel < ActiveRecord::Base
  include DiscoApp::Concerns::CanBeLiquified

  ... rest of model definition ...
end

with this in your application's app/views/my_model/show.html.erb:

<%= raw @my_model.to_liquid %>
{% include 'my_model-show' %}

and finally something like this in your theme's snippets/my_model-show.liquid:

{% layout 'theme' %}
<h1>{{ my_model_name }}</h1>
<p>
  {{ my_model_description }}
</p>

Administration

There is a standard administration site for the app, located at /admin. It provides a filtered list of shops that have installed the app, a way to manage plans and plan codes for the application, and a page to manage application-wide settings.

This admin section is secured via HTTP basic authentication. In order to define the username and password to access this section of the app, fill in the following variables to the generated app .env.local file:

ADMIN_APP_USERNAME=
ADMIN_APP_PASSWORD=

Application-wide settings should be added to the DiscoApp::AppSettings model. At the controller level you can can permit the new params by overriding the admin controller at: app/controllers/disco_app/admin/app_settings_controller.rb.

class DiscoApp::Admin::AppSettingsController < DiscoApp::Admin::ApplicationController
  include DiscoApp::Admin::Concerns::AppSettingsController

  private

    def app_settings_params
      params.require(:app_settings).permit(:default_recurring_price, :trial_days, :test_charges, :mailchimp_api_key, :mailchimp_list_id, :sidebar_message_enabled, :sidebar_message)
    end

end

At the view level, you should override app/views/disco_app/admin/app_settings/edit.html.erb in order to add fields for the new settings you've created.

Helpers

A number of view helpers designed to encapsulate common Shopify app functionality are included with the gem and are automatically imported and made available from within the main application helper.

link_to_shopify_admin

Generates a link pointing to an object (such as an order or customer) inside the given shop's Shopify admin. This helper makes it easy to create links to objects within the admin that support both right-clicking and opening in a new tab as well as capturing a left click and redirecting to the relevant object using ShopifyApp.redirect().

<%= link_to_shopify_admin(@shop, 'Order 1234', "orders/1234") %>

link_to_modal

Generates a link that will open its given href inside an embedded Shopify model.

react_component_with_content

Renders a react component with inner HTML content.

errors_to_react

Provides detailed information from an ActiveRecord to JSON object. Useful for passing the information into React components.

  <%= react_component('ExampleResourceForm', @example_resource.as_json.merge({
    errors: errors_to_react(@example_resource)
  })) %>

Extending Models

The models that come with the DiscoApp engine (such as DiscoApp::Shop) can be extended through the use of Rails Concerns (see Overriding Models in the official Rails Guides for an idea how this works).

Here's the example used inside the "dummy" app used for testing the engine:

require 'active_utils'

class DiscoApp::Shop < ActiveRecord::Base
  include DiscoApp::Concerns::Shop

  # Extend the Shop model to return the Shop's country as an ActiveUtils country.
  def country
    begin
      ActiveUtils::Country.find(data[:country_name])
    rescue ActiveUtils::InvalidCountryCodeError
      nil
    end
  end

end

Synchronising Models

In many situations, it's useful to store a version of a Shopify resource in our application's local database. Disco App provides a way to simplify the process of keeping this local version in sync with the version on Shopify with a concern (DiscoApp::Concerns::Synchronises).

The steps below walk you through what you need to do for the implementation of synchronisation of product resources as an example. You can also refer to the implementation of this inside the dummy app used for testing Disco App in test/dummy/app/models/product.rb and test/dummy/app/jobs/products_*.rb.

1. Create a local model to represent the resource, for example a Product model. Make sure it includes a shop_id foreign key referencing its owning DiscoApp::Shop and a data attribute with a JSONB datatype.

2. Include the Synchronises concern to the model class, along with the belongs_to association:

   class Product < ActiveRecord::Base
     include DiscoApp::Concerns::Synchronises
     belongs_to :shop, class_name: 'DiscoApp::Shop'
   end

3. Add background jobs to handle possible webhook calls we could receive to keep the information updated (eg products/create, products/update, products/delete) and ensure these webhooks are registered on application installation. Implement these jobs to simply call the synchronise or synchronise_deletion method as appropriate, eg:

   class ProductsCreateJob < DiscoApp::ShopJob
     def perform(_shop, product_data)
       Product.synchronise(@shop, product_data)
     end
   end

4. You may want to perform an initial synchronisation of resources. To do this, the Synchronises concern provides a synchronise_all method. For this to work, you must define a SHOPIFY_API_CLASS constant on your model class, for example:

   class Product < ActiveRecord::Base
      include DiscoApp::Concerns::Synchronises
      belongs_to :shop, class_name: 'DiscoApp::Shop'
      SHOPIFY_API_CLASS = ShopifyAPI::Product
   end
   

   You can then call the synchronisation with Product.synchronise_all(shop).

This should be all you need to do to have your local models stay up to date with any changes made by the store owner on Shopify. If needed, you can override the individual should_synchronise?, synchronise, should_synchronise_deletion? and synchronise_deletion class methods on your model. For example, if you only wanted to synchronise products of a particular type, you could implement:

class Product < ActiveRecord::Base
  include DiscoApp::Concerns::Synchronises
  belongs_to :shop, class_name: 'DiscoApp::Shop'

  def should_synchronise?(shop, data)
    data[:product_type] == 'Shoes'
  end
end

Model Metafields

If you're writing resource metafields for your models via the Shopify API, you can include DiscoApp::Concerns::HasMetafields to gain access to a convenient write_metafields method. Just make sure that SHOPIFY_API_CLASS is defined on your class, that you're calling the method in an API context, and away you go:

class Product < ActiveRecord::Base
  include DiscoApp::Concerns::HasMetafields

  SHOPIFY_API_CLASS = ShopifyAPI::Product

end

product = Product.find(12345678)

@shop.with_api_context do
  product.write_metafields(
    namespace1: {
      key1: 'value1',
      key2: 'value2
    },
    namespace2: {
      key3: 'value3'
    }
  )
end

This also works for shop metafields, although be aware that in this case each metafield requires an individual API call:

class DiscoApp::Shop < ActiveRecord::Base
  include DiscoApp::Concerns::HasMetafields

  SHOPIFY_API_CLASS = ShopifyAPI::Shop

end

# this works, but results in 3 API calls
@shop.with_api_context do
  @shop.write_metafields(
    namespace1: {
      key1: 'value1',
      key2: 'value2
    },
    namespace2: {
      key3: 'value3'
    }
  )
end

Note also that write_metafields includes an API call out to fetch any existing metafields for the object, so that it can avoid any namespace and key conflicts by updating existing metafields rather than trying to create new ones.

Rubocop

DiscoApp adds support for Rubocop and Codeclimate. the .rubocop.yml contains the configuration you can tweak to suits your coding style, by enabling/disabling "Cops" accordingly.

Email Support

DiscoApp has support for the Mailgun and configures Active Mailer to use the Mailgun API in production for sending email. Adds the MAILGUN_API_KEY and MAILGUN_API_DOMAIN environment variables.

Monitoring

DiscoApp has support for both exception reporting and application performance monitoring to the application.

Appsignal is used for exception tracking, and will be activated when a APPSIGNAL_PUSH_API_KEY environment variable is present. The Appsignal Push API Key can be found in 1Password.

New Relic is used for application performance monitoring, and will be activated when a NEW_RELIC_LICENSE_KEY environment variable is present. There is a single New Relic license key across all Disco apps - contact Gavin if you need it to deploy a new application.

Upgrading

To upgrade your application from a previous version of the gem, these are the steps you should take:

• Update the disco_app entry in your Gemfile to point to the latest tagged release of the gem (check the release list to find the latest available version).
• Run bundle update. You may have to resolve some gem dependencies.
• Run rails disco_app:install:migrations to copy over any new migrations from the gem into your application, ready to be run with a rails db:migrate.
• Carefully read through CHANGELOG.md, UPGRADING.md, and the commit history for disco_app between the previous version of the gem you were using and the new one. You may have to make some changes to your application code to adapt to change.

Troubleshooting

A list of common problems folks encounter when setting up or building apps with DiscoApp.

During install: Nokogiri / libxml2 reported missing

Try the following:

$ xcode-select --install
$ gem install nokogiri -- --use-system-libraries --with-xml2-include=/usr/include/libxml2 --with-xml2-lib=/usr/lib/

During install: General

Try the following to restart Spring:

$ spring stop
$ bin/spring

During Oauth: Redirect URI is missing or not listed

Check that:

• You're accessing the application via HTTPS, not HTTP;
• You've correctly set DEFAULT_HOST in your local ENV;
• You've correctly listed the redirect URI in the app on the partner dashboard.

Scheduled tasks aren't running

Check that you've added the tasks to the server. This will look something like:

  dokku_apps:
     - name: app-name
       plugins: ['redis']
       tasks:
         - name: run scheduled imports (every 30 minutes)
           job: rake run_scheduled_imports
           minute: "0,30"
         - name: run scheduled fetches (every 5 minutes)
           job: rake run_scheduled_fetches
           minute: "*/5"

Don't forget to provision the server after making changes: ./provision.sh server-name.

Webhooks aren't firing

This is a pretty common problem and can be cause by a number of things. You can check if your webhook has registered by running shop.with_api_context{ShopifyAPI::Webhook.find(:all)} in a Rails console, where shop = DiscoApp::Shop.find(your_shop_id). If it isn't registered, check the following things:

1. Check you've run the rake webhooks:sync task
2. Check you've added the webhook topic to config/initializers/disco_app.rb and it's spelled correctly
3. Ensure you have a background job set up and named correctly with a perform method
4. Run DiscoApp::Shop.installed.has_active_shopify_plan from a console. If this doesn't return an active plan make sure shop.status is set to 'installed'.

If you encounter other speedbumps with webhooks please add then to this list.

Contributing

While developing Shopify applications using the DiscoApp Engine, you may see something that could be improved, or perhaps notice a pattern that's becoming common across a number of applications.

In those cases, please consider taking the time to raise an issue or pull request against the DiscoApp repository. If contributing code, please make sure to update the relevant section of this README as well.

Releasing

To create a new release of the application:

1. In general, follow the instructions for releasing an app to production with git flow.
2. During Step 3 of the release process, in addition to bumping the version number in the VERSION file, you should:
   1. Also update the version number in version.rb to match VERSION;
   2. Ensure the CHANGELOG is up to date by reviewing all commits since the last release;
   3. Ensure the UPGRADING file contains all necessary instructions for upgrading an application to the latest version of the gem;
   4. Update initialise.sh to point to the latest version number of the gem.
3. Once the git flow release steps have been completed, ensure you have the latest version of the master branch and push to Gemfury. See uploading packages to Gemfury for instructions on this step if you haven't done it before.

License

DiscoApp is released under the MIT License.